The objective of this proposed effort is directed towards the development of a periodontal temperature probe with response time and sensitivity characteristics which can potentially provide an objective and simple diagnostic technique in assessing periodontal disease activity. Studies have suggested that inflamed sulci are accompanied by elevated temperatures indications. Conventional techniques, such as bleeding upon probing, suppuration, or gingival redness are highly subjective diagnostics with respect to the detection of active diseases. The temperature sensing element of the proposed probe is imbedded in the probe tip. The tip shape and size are similar to conventional periodontal probes with Williams markings. The advantages of such a probe are (1) the concurrent measurement of sucular temperature and attachment level, (2) the identical probe insertion technique used in conventional attachment level measurement, and (3) the rapidity in allowing for multiple-site evaluation of disease activity. The key feature of this probe which allows the faithful measurement of sulcular temperature is the specially designed low thermal mass of the probe tip. This feature provides minimal perturbation to the regional tissues thus allowing for a measurement accuracy of better than 0.1 degree C and a response time of less then 2 seconds. The Phase I program which this proposal addresses is concentrated towards the fabrication and in vitro testing of such a probe for its reproducibility, sensitivity, and response time. Preliminary in vivo study will be performed to relate temperature to periodontal disease activity. The Phase II program will be oriented towards the clinical validation of sulcular temperature changes accompanying disease activity. Probes with such special features are not currently available to clinicians. The simplicity of the concept and the similarity in dimensions to a conventional periodontal probe would greatley enhance its eventual marketability.